Industrial furnace built of radiating elements



A. BIRO 3,473,795 Y INDUSTRIAL FURNACE BUILT OF RADIATING ELEMENTS Filed Nov. 28, 1967 Fig. I

Fig. 2

INVENTOR. T774 ,1 6/20 firrvr.

United States Patent 3,473,795 INDUSTRIAL FURNACE BUILT 0F RADIATING ELEMENTS Attila Biro, Miskolc, Hungary, assignor to Koho-es Gepipari Miniszterium Tuzelestechnikai Kutatointezet, lVIiskolc, Hungary Filed Nov. 28, 1967, Ser. No. 686,139 Claims priority, application Hungary, Jan. 30, 1967, B1 270 Int. Cl. F27b 5/00; F2311 13/24 US. Cl. 263-41 7 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to an industrial furnace for carrying out metal-technologic operations of any type, having an entirely encircled hearth. The furnace consists of a plurality of prefabricated, removable radiating elements and a framework. The radiating elements are provided on their inner side turned towards the hearth with a firing space built behind the radiating wall, and their outer side opposite to the hearth is provided with heat insulation reducing the heat loss. The elements are also provided with means serving to introduce the fuel and the fire-feeding air into the said firing space and with means to exhaust the combustion products. The radiating elements are fastened to one another and to the said framework by releasable coupling-elements.

The invention relates to a heat-treating furnace built of radiating elements for carrying out various metaltechnologic operations.

With one type of the known heat-treating furnaces the metal objects to be heated are put into the furnace hearth limited by a refractory wall into which flue gases produced by the firing of a gaseous, a liquid or a solid fuel are introduced. The heat-treating furnaces of this type have the drawback of detrimental deformations appearing on the surface of the material to be heat-treated, due to the contact with flue gases. The dimensions of the hearth of this furnace type cannot be altered after construction.

With another type of heat-treating furnace the metal objects to be heated are accommodated in a refractory case (muffle) which is built into the furnace and the firing takes place in the space between the outer surface of the case and the furnace wall. In this way, the material to be heat-treated is not in contact with the flue gases. This design has, however, the drawback of being serviceable only with small-dimension furnaces, and also of the useful hearth being relatively small as compared with the effective internal dimensions of the furnace. The dimensions of this furnace type can neither be altered and the construction thereof is rather expensive.

With a third known type of furnaces the firing takes place in enclosed radiating tubes protruding into the furnace hearth. There is no contact either between the material to be heat-treated and the flu gases. A drawback of this system is that those sides of the radiating tubes which lie closer to the furnace jacket grow more hot, whereby limits are set to the maximum temperature that can be produced in the furnace. When using a small number of radiating tubes, a relatively great dilference arises between the temperatures at various points in the hearth, which is disadvantageous. The furnace dimensions can in this case not be altered either.

With the fourth group of heat-treating furnaces known so far, the heating required for heat-treatment is effected by means of electric power. The charge of this type of furnace is neither in contact with the line gases and the heat transfer can be made more uniform. This design 3,473,795 Patented Oct. 21, 1969 has, however, the drawback that electric power is more expensive than all other fuel systems, and that the furnace dimensions are equally unalterable.

The invention aims at bringing about a heat-treating furnace wherein the deficiencies of the known furnace types are eliminated, the operation being inexpensive, the material to be heated not being in contact with the flue gases during the heat-treating process, the heat transfer being uniform at various points in the furnace hearth, the furnace being assemblable of prefabricated elements in a quick and simple way, the shape of the furnace hearth being alternable in a quick way and by simple means.

The task aimed at is solved by the invention by means of special radiating elements. In these elements there is a chamber suitable for receiving the flue gases and for carrying out the combustion process. The combustion chamber is bordered by a thin metallic wall, a so-called radiating wall towards the furnace hearth. Coupling elements link the individual elements with one another and with the framework of the furnace on four sides of the elements.

In order to carry out the various metal-technologic operations the heating furnace according to the invention so designed that the hearth thereof is encircled entirely by radiating elements fixed to one another and to the framework of the furnace by means of releasable joints of any known type, or instead of some of the radiating elements cooling, mixing or insulating elements are provided that are similarly connected to the framework and to the other surrounding radiating elements, wherein each radiating element is provided on its inner side lying towards the furnace hearth with a firing space built behind the radiating wall, whereas on its outer side opposite to the furnace hearth it has heat insulation in order to reduced its heat losses; each radiating element is fitted also with means to introduce the fuel and the firefeeding air into the firing space, and to exhaust the combustion products.

The invention has the advantage of the furnace being quickly installable and entirely gas-tight, whereas the workpiece is heated uniformly by the radiation of the Whole wall surface. Another advantage lies in that the elements of the furnacesimilarl to the construction setscan be made any shape or size, and that the radiating elements of standard size are replaceable by elements of the same size, connected in a simple and similar way to the frame work of the furnace and to the other radiating elements. So, for instance, a mixing fan, or simply nothing but an insulating element made of refractory material can be inserted in the place of the radiating elements.

The invention is described hereunder with reference to an embodiment shown by way of example in the drawing. In the drawing FIGURE 1 shows the schematic side elevation of the furnace by way of example, Whilst FIG- URE 2 represents the schematic section of one of the radiating elements.

To a framework 1 shown in FIGURE 1 radiating elements 3 bordering and encircling the furnace chamber are fixed by clamps 2. Heating of the radiating elements 3 is effected through a fuel conduit 4. The fuel comes from the fuel conduit 4 into firing devices 5, the amount thereof being regulable by means of cocks 6 built into the conduit. Owing to the burning process taking place in the radiating elements combustion products are generated and flow through connecting branches 7 of the radiating element into a smoke collecting conduit 8. Introduction of the material to be heat-treated into the furnace chamber and its removal therefrom are effected through a furnace door 9 of the usual design, disposed against the head wall of the furnace.

The fuel comes from generator space 12 into firing space 11 of the radiating element shown in FIGURE 1. With each generator any known type of burning device can expediently be used that gives a flame preferably perpendicular to its own longitudinal axis. The fuel flows through a tube 13 into the generator space 12, whereas the fire-feeding air is conducted through a preheating space 14 and through a tube 15 to the flame. The flue gas produced in the firing space 11 transmits a great part of its heat content to the radiating wall 16 and flows out through a tube end 7 into a smoke collecting conduit. In order to reduce the heat loss, the radiating element 3 is provided with a screening plate 18 and with an insulating board 19 filled with insulating material. The air space arranged on both sides of the screening plate 18 serves equally the purpose of heat insulation. That surface of the radiating elements 3 which lies towards the outer side of the furnace is covered with a corrugated aluminum sheet 17 serving equally to reduce the radiation heat loss. The radiating elements 3 can be airtightly interconnected by any known method, e.g. by means of welding together fastening elements 20 fixed to the body of the element.

Experience has shown that radiating elements of abt. 1 sq. m. radiating surface are the most expedient, but, in a given case, the size of the elements may be altered or possibly standardized in several sizes.

The invention is adaptable with excellent results for carrying out the most various metal-technologic operations: annealing, drying, tempering, hardening, casehardening, nitriding, and for combinations of the above operations.

I claim:

1. An industrial furnace for carrying out operations on metal workpieces, the furnace being an assembly of a plurality of removable radiating elements, a framework on which said elements are supported, releasable coupling elements by which the radiating elements are connected to each other and to said framework, said radiating elements encircling and defining within them a heating chamber, said radiating elements having gas-impermeable radiating walls on their inner side facing the chamber 4 and having heat insulation on their outer side opposite the chamber, said radiating elements each having a firing space between the radiating wall and the insulation. means to introduce fuel and combustion air into said firing space, and means to exhaust combustion products from said firing space.

2. Industrial furnace as claimed in claim 1, said radiating elements being in the form of modular wall-forming elements from which at least a portion of the walls of the furnace are constructed.

3. Industrial furance as claimed in claim 1, in which the said radiating elements are interchangeable among themselves.

4. Industrial furnace as claimed in claim 1, in which the radiating elements are provided with means serving for connecting them to one another in an airtight way.

5. Industrial furnace as claimed in claim 1, in which the radiating elements are provided with a preheating space for the preheating of the combustion air being developed on the outer side of radiating elements.

6. Industrial furnace as claimed in claim 1, in which each radiating element has at least one flue gas outlet tube to exhaust the combustion products.

7. Industrial furnace as claimed in claim 1, in which each radiating element has at least one flue gas outlet tube to exhaust the combustion products, and the Whole equipment is provided with one common smoke-collecting and exhausting conduit.

References Cited UNITED STATES PATENTS 2,494,530 1/1950 Tuttle 263-42 2,960,980 11/1960 Williams et al.

3,020,032 2/1962 Casey 26342 3,368,802 2/1968 Morgan et al. 263-46 JOHN J. CAMBY, Primary Examiner US. Cl. X.R. 431350 

